1. Field of the Invention
The present invention relates generally to an apparatus and method for performing a medical procedure. More specifically, the invention provides for identifying target tissue margins and for guiding a tissue resection device to the target tissue in a tissue resection procedure.
2. Description of the Related Art
An endoluminal procedure is a medical procedure that takes place in one of the many tubes, or lumens, within the human body. The endoluminal procedures may take place in vascular, gastrointestinal, or air exchange lumens, and may involve disease diagnosis and/or treatment. Millions of endoluminal procedures are performed each year in hospitals around the world.
A procedure that is often carried out endoluminally is the removal of “suspect” or diseased tissue. The purpose of such tissue removal, or resection, may be to provide tissue samples for histological analysis or removal of diseased tissue as a treatment means. Today, endoluminal resection of tissue is often done using only the subjective judgment of the clinician to determine where tissue should be removed. As disease tissue margins are sometimes difficult to determine visually, tissue resection guided solely by visual cues can be inaccurate and even dangerous. The danger arises when resectioning cancerous tissues that are prone to metastasize. In this case, a tissue resection that occurs without sufficient buffer of healthy tissue risks leaving behind cancerous tissue requiring repeated resectioning procedures, or worse, causing the cancerous lesion to “seed”, or metastasize, to other parts of the body.
FIGS. 1 and 2 illustrate a prior art endoluminal device 100 that could be used in the harvesting of diseased tissue from within a body lumen. The device is comprised of a flexible catheter body 110 with a proximal end 112 and distal end 114. At the proximal end 112 there is a suction adjust knob 120, a coupler 130, a vacuum hose 140, head-actuating handle 150, and an electrical interconnect 160. The vacuum hose 140 makes connection from a vacuum pump 142, through the coupler 130, to a central lumen 170 within the catheter body 110 to draw a suction on tissue-harvesting chamber 190. The electrical interconnect 160 is comprised of electrical leads 161 that pass from the external electronics 162, through the coupler 130 at the proximal end 112 of the catheter body 110 to a cavity 116 outside the central lumen 170 but within the catheter body 110. Some of the electrical leads 161 supply electrical energy to a light source 163 and a vision chip 164 situated at the distal end 114 of the catheter 110, while another group of the electrical leads 161 bring electrical signals from the vision chip 164 to a video processor and a display device 165. The head-actuating handle connects to a cable (not shown) that travels the length of the catheter body 110 within the central lumen 170 to control the operation of the endoluminal device's head assembly 180.
FIG. 2 is a detailed view of the distal end 114 of the device 100 of FIG. 1. At the distal end 114 of the catheter body 110 there is a head assembly 180, a tissue-harvesting chamber 190, a cutting device 192, and the light source 163 and the vision chip 164. The tissue-harvesting chamber 190 is connected to the central lumen 170 of the catheter body 110. The central lumen 170 is connected to the external vacuum pump 142. The head assembly 180 is movable with respect to the catheter body 110 and, thus, can be extended or retracted using the cable that is attached to the head-actuating handle 150 at the proximal end 112 of the device 100 and to the head assembly 180 at the distal end 114 of the device 100. The cutting device 192 is a sharpened blade that severs the tissue 200 as the retracting head assembly 180 presses the tissue 200 against the cutting device 192 to remove the suspect tissue area 210. Distal end 114 also includes staples 194 and anvil surface 196 which are utilized to staple the site. The vision chip 164 is connected to the external video processor and display device 165 via the electrical leads 161 within the catheter body 110, but outside of the central lumen 170.
FIG. 2 also illustrates the distal end 114 of the prior art tissue-resectioning device 100 as it would appear having been inserted into a body lumen. Extended into the body lumen, the Endoscopist would guide the distal tip 114 of the device into close proximity with the tissue 200 to be resected. By adjusting the suction at the tip 114 with the suction adjust knob 120, the clinician can then increase the suction at the tip 114 until the tissue 200 is drawn into the tissue harvesting chamber 190 through a distal opening 114A and into the tissue harvesting chamber 190. Once the tissue is in position, the clinician can then retract the head assembly 180 to perform the resection. The suspect tissue 210 is removed and the site is stapled with the staples contained in the head assembly 180. With the tissue sample 210 enclosed within the tissue-harvesting chamber 190, the device 100 can be removed from the body lumen and the tissue sample 210 removed.
Today, a tissue-resectioning procedure such as described above would be guided by the clinician based upon whatever limited visual information could be obtained through the vision chip 164 at the distal end 114 of the catheter 110. Whereas histological staining may be used to assist in tissue margin identification, guiding the resection device 100 in the procedure in this manner is still a very subjective process and prone to error. There is a high probability that either too much or too little tissue will be resected. Both of the outcomes are undesirable, and even dangerous.
Therefore, it would be desirable to provide an improved system and method for assisting a practitioner in accurately identifying target tissue margins and guiding the practitioner to the target tissue.